Emergency notification systems typically include a plurality of notification appliances, such as strobes and horns, for providing occupants of a building with a prominent visual or auditory indication of a hazardous condition, such as the presence of smoke or fire. Typically, a notification appliance is attached to an electrical backbox, which in turn is mounted on a wall or ceiling surface (e.g., surface mounted or wire mold mounted) or embedded in a wall. Electrical leads or wires extend from a notification system circuit into the backbox through knock-outs in the rear or sides of the backbox. A mounting plate is typically used to attach a notification appliance to the front of the backbox, with audible and/or visual alarm-generating elements of the notification appliance fastened to the mounting plate and having electrical leads extending through the mounting plate and into the backbox. A rigid housing is typically mounted over the audible and/or visual alarm-generating elements, and a removable cover is mounted over the housing, thereby providing the notification appliance with a secure enclosure.
At times, it may be necessary or desirable to remove the cover of a notification appliance from the appliance's housing, such as for replacing the cover if it is damaged, for accessing and adjusting the operational settings of the notification appliance, or for painting a portion of a wall or ceiling immediately adjacent the notification appliance. Many conventional notification appliance enclosures include covers that are secured to respective housings with one or more screws or other mechanical fasteners that must be fastened and unfastened with a tool during mounting and removal of the covers. Such fastening and unfastening can be tedious and time-consuming, especially when aggregated over a large number of appliances that may be part of an overall emergency notification system. In spite of this, screws and other such fasteners are used because they provide appliance enclosures with sufficient robustness to satisfy industry standards. For example, Underwriters Laboratories (UL) requires that notification appliance enclosures be able to withstand certain impact forces without opening or being significantly damaged.